JPS5879090A - Oxidation accelerator for sulfur dioxide in cracking process - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The scope of fluid catalytic cracking involves the catalytic cracking of heavy hydrocarbons into commercial fuels and petrochemical feedstocks. A catalytic cracking (FCC) unit has a hydrocarbon cracking zone and a catalyst regeneration zone. A finely divided catalyst, typically containing zeolite, is circulated between a cracking zone where the hydrocarbon feedstock is cracked and a regeneration zone where coke that forms on the catalyst in the cracking zone is burned off. The combustion gases formed in the regeneration zone always contain some harmful substances, which are considered air pollutants. For example, carbon monoxide is commonly formed during the process of oxidizing coke. US Patent No. 3
, No. 909.392. Furthermore, if the hydrocarbon feedstock contains sulfur and/or nitrogen, the combustion gas will typically contain various tr oxides of these elements.

Carbon monoxide contained in the combustion gas can be controlled by adding a carbon monoxide oxidation promoter such as platinum. See US Pat. No. 4,072,600. sulfur sorbent
), for example, alumina in a circulating inventory (cir
The sulfur oxides can be controlled by including the sulfur oxides in the cracking catalyst, i.e., by mixing them with cracking catalysts. See US Pat. No. 4,071,436. It has also been recognized that the inclusion of a sulfur dioxide oxidation promoter accelerates the removal of sulfur from the combustion gas by the sulfur absorbent.

See US Pat. No. 4,115.250. To date, one of the most effective sulfur dioxide oxidation promoters has been platinum. Although effective, this promoter has the disadvantage of increasing the amount of nitrogen oxides contained in the flue gas. As mentioned above, platinum also acts as a carbon monoxide oxidation promoter. - It would be desirable to be able to use an oxidation promoter in the regeneration process that retains the effectiveness of platinum in promoting the oxidation of carbon oxides and sulfur dioxide, yet does not form nitrogen oxides.

Palladium and at least one member selected from the group consisting of platinum, osmium, iridium, rhodium, and rhenium.
It has been discovered that certain metal mixtures containing other metals serve as oxidation promoters for carbon oxide and sulfur dioxide while minimizing the formation of oxides of nitrogen. Even more surprisingly, it has been discovered that the pro-oxidation effect of sulfur dioxide in these mixtures is always greater than the effect of the individual metals used to form the mixture. It is also noteworthy that we have found that the ability to promote the oxidation of sulfur dioxide is enhanced and the amount of nitrogen oxides formed is significantly reduced compared to using platinum alone. .

Accordingly, the present invention provides for circulating a circulating catalyst population containing particulate cracking catalyst between a hydrocarbon cranking zone and a catalyst regeneration zone, and providing a sulfur oxide absorbent within the circulating catalyst population. In an improved fluid catalytic cracking process for controlling the sulfur content of the gas exiting the regeneration zone by including palladium or a palladium compound and at least one member selected from the group consisting of platinum, osmium, iridium, rhenium and rhodium. A sulfur dioxide oxidation promoter formed in intimate association with another metal or a compound thereof is included in the regeneration zone in association with an inorganic oxide support.

The present invention further provides a particulate cracking catalyst comprising: (a) a particulate cracking catalyst for cracking hydrocarbons in the absence of hydrogen; (b) a sulfur absorbent capable of absorbing sulfur trioxide; is a different first particulate solid, and (C) palladium or a palladium compound, and platinum,
A catalyst different from the particulate cracking catalyst, comprising an inorganic oxide support in association with a metal mixture containing at least one other metal selected from the group consisting of osmium, iridium, rhenium and rhodium, or a compound thereof. The present invention relates to a composition useful for cracking sulfur-containing hydrocarbons in the absence of added hydrogen, characterized in that it comprises particulate solids of 2.

The present invention further provides a particulate cracking catalyst consisting essentially of (a) a silica-containing Clara catalyst impregnated with an aluminum compound capable of absorbing sulfur oxides, and (b) palladium or a palladium compound. ,platinum,
Different from the finely divided Clara catalyst, the catalyst comprises an inorganic oxide support associated with at least one other metal or compound thereof selected from the group consisting of osmium, iridium, rhenium and 11dium. The present invention relates to a composition useful for cracking sulfur-containing hydrocarbons in the absence of added hydrogen, the composition comprising a second particulate solid.

The "one-cycle catalyst mass" refers to the fine-grained solids that are circulated between the cracking zone and the regeneration zone.

Accordingly, this BH material includes, but is not limited to, a Klutney Young catalyst, a particulate sulfur absorbent, and accelerator particles.

As used herein, the term "sulfur absorbent" refers to a sulfur absorbent that is capable of forming a stable association with sulfur trioxide in the regeneration all of the FCC unit and that is capable of separating in the hydrocarbon cracking zone. Refers to matter. This association may be formed by absorption, adsorption or chemical reaction. Such sulfur absorbers include alumina and magnesia. Particularly preferred as a sulfur absorbent is "responsive alumina", which is e.g. γ- or η-
Alumina may be defined as an alumina having a surface area of at least 5012/(1). Preferred reactive aluminas are not closely associated with more than about 40% silica and are substantially free of silica. Preferably, they are not mixed.For more information on reactive alumina, please see
No. 4,071,436, which is incorporated by reference as part of Honkawa aS.

The present invention is directed to an improved class of oxidation promoters that are highly effective in converting sulfur dioxide to sulfur trioxide. In most cases, the prooxidant also serves as a prooxidant for converting carbon monoxide to carbon dioxide.

The accelerator disclosed by Honkawa Seisen has selectivity for the accelerating effect of converting sulfur dioxide into sulfur trioxide, and also minimizes the formation of nitrogen oxides, so that it can achieve this effect. This class of accelerators is particularly advantageous. The relative proportions of palladium to other metals vary widely depending on the metal used and the operating method selected.

Generally, when only one other metal is included in association with palladium, the relative weight ratio between these one metals will be about 100:1 to 1:100, preferably about 10:1.
It is within the range of 1 to 1:10.

Promoters containing palladium and iridium (10:1) and palladium and platinum (10:1) are particularly preferred for promoting the oxidation of sulfur dioxide. It is important to deposit these metals on the support as a mixture of metals. It has been found that when dissimilar metals are placed in separate particles J, the ability of the metals to promote oxidation of the sulfur dioxide product is significantly reduced.

The support used in conjunction with the promoter may be any inorganic oxide that does not adversely affect the activity of the promoter or the operation of the FCC unit.

Preferably, the support is a finely divided solid that can be physically mixed with and recycled with the cracking catalyst and sulfur absorbent. Such materials include porous inorganic oxides such as alumina and silica;
species or mixtures of one or more inorganic oxides, e.g. silica
Included are crystalline aluminosilicate zeolites, such as alumina, natural and synthetic silanes, and the like. Preferred supports are porous cracking catalysts that exhibit good attrition resistance within the FCC unit and prevent loss of promoter outside the system. 1 Engelhard
) is suitable for use as a support for the promoter.

The metal can be added to the support by any suitable method such as impregnation or ion exchange, or alternatively by co-precipitation from an aqueous solution with an inorganic oxide precursor. It can also be added to the precursor of the support. In the case of finely divided accelerator-supports, the F is applied, for example by spray drying, or by grinding large particles to the desired size, or by other conventional means.
Particles of suitable dimensions for use in CC systems can be fused to form finely divided solids.

In incorporating the promoter into the circulating catalyst population of the FCC unit, sufficient promoter should be included to promote the oxidation of sulfur dioxide to sulfur monoxide. moreover,
If it is desired that the prooxidant also serve as a promoter for the conversion of carbon monoxide to carbon dioxide, a sufficient amount of the promoter must be included to assist in this reaction. In general, the amount of promoter required to oxidize carbon oxide is less than that required for oxygen in sulfur dioxide, so the amount of promoter required to oxidize carbon oxide is less than that required for oxygen in sulfur dioxide. normally does not need to be considered. Generally, the total metal content of the promoter is from about 0.01 to about 2% of the promoter-support association and from about 0.01 to about 100% of the total circulating catalyst population.
i4' occupies 1) I) m.

Preferably, the sulfur absorbent included in the circulating catalyst population is reactive alumina. However, other sulfur absorbers are also described in the literature and can be used in the present invention. Generally, a suitable sulfur absorbent should have the ability to absorb at least about 50 φ-% of the sulfur oxides present in the regeneration zone. In the case of reactive alumina, the sulfur absorbent particles typically contain at least 60% by weight alumina. This alumina is at least 501
2/(l) and contains about 0.1 to 100 weight percent reactive alumina. Typically, the sulfur absorbent contains about 0.1 to about 25 weight percent of the total circulating catalyst population. The sulfur absorbent is generally included with the catalyst in an amount sufficient to
Contained as a finely divided solid physically mixed with catalyst particles and promoter particles. However, U.S. Patent No. 4,115.2
49, the sulfur absorbent is
It may also be present on the particles.

The catalyst used for cracking hydrocarbon feedstocks is FC
It can be any catalyst suitable for use with C systems. Catalysts of this type usually contain silica and/or alumina. Other refractory metal oxides such as magnesia and zirconia have been suggested and can be used if desired. Various types of naturally occurring and synthetic fufluminosilicate molecular sieves are commonly added to cracking catalysts. The selection of catalyst is not a critical element of the invention. The catalyst selection criteria appears to be determined by the feedstock to be cracked and the method of operation rather than the oxidation promoter selected. Therefore, the selection of catalyst is within the discretion of those skilled in the art and does not require detailed explanation here.

Various other types of materials can be included in the circulating catalyst population on the FCC]CC, provided they do not substantially interfere with the activity of the metal promoter.

Additional carbon monoxide oxidation promoters such as copper or chromium may be added. Along with alumina, sodium was also used as a sulfur absorbent. This kind of substance does not pose a problem in carrying out the present invention if it is of an appropriate age.

Palladium and iridium (10:1) and palladium and rhodium (10:1) are used to control the formation of nitrogen oxides.
Particularly preferred are pro-oxidant mixtures of 0:1).

Particularly preferred is a mixture of palladium and iridium, which has an excellent effect of promoting the oxidation of sulfur dioxide to panicle trioxide.

For a clearer understanding of the invention, please draw attention to the following table. Equilibrium catalyst HEZ-5 with various oxidation promoters by impregnation method
The ability of individual metals to oxidize sulfur dioxide to sulfur trioxide was indirectly determined by placing them on alumina and examining the adsorption rate of sulfur trioxide on alumina. The table is 3
The activity is shown when a selected type of metal catalyst is used alone.

111L1 So, l, /
) Platinum 0.1% 599 Palladium 0.1% 491 Iridium 0.1%
318 Regarding this table, it should be noted that of the three metals, platinum is by far the best oxidation promoter. It can be seen that iridium has extremely low ability to promote oxidation.

As previously mentioned, the ability of the metal mixture disclosed herein to selectively promote the oxidation of aia dioxide while minimizing the formation of nitrogen oxides provides advantages not seen in the prior art. It is something that brings. This becomes clear when referring to FIG. FIG. 1 shows the activity of the individual metals listed in the table above and of various mixtures of the 11 metals within the scope of the invention. It can be seen from FIG. 1 that all of the metal mixtures tested had improved activity as a sulfur dioxide promoter compared to the individual metals used to make the mixtures. At the same time, it can also be seen that the amount of nitrogen oxides formed by these metal mixtures was significantly reduced compared to when platinum was used alone. The data for 1B is from a total of 0.1% gold superimposed on the support.

Particularly active sulfur dioxide oxidation promoters are mixtures of palladium and iridium (10:1) and mixtures of palladium and platinum (10:1).

Referring to FIG. 2, the effect of varying the ratio of palladium to platinum on the promotion of oxidation of sulfur dioxide is compared. This figure shows that various mixtures of platinum and palladium exhibit a true synergistic effect, i.e., a greater oxidation promoting effect than either metal alone.
It can be seen that their mixture shows. The best oxidation promoting effect is obtained when the ratio of palladium to platinum is about 1:1, but from an economical point of view, it is recommended to operate with less platinum in the mixture than is optimal. It is usually desirable to do so. This is due to the higher cost of platinum compared to palladium.

[Brief explanation of drawings]

Figure 1 compares the ability of various metals and metal combinations to promote the oxidation of sulfur dioxide and the degree of formation of nitrogen oxides, and Figure 2 shows the synergistic effects of various palladium/platinum mixtures on oxidation of sulfur dioxide. This is a graph showing the effect. Purity of the drawings of four agents, Asahi and Kōgai! ! '(No change in content) FIG, l. FIG, 2゜Procedural Amendment (Method) Showa! Mr. Commissioner of the Japan Patent Office 1, Case Description Showa G7 Patent Application No. 1117. f/B No. 3, Address of the person making the amendment 4, Agent 5, Date of amendment order April 39, 1955 6, Number of inventions to be increased by the amendment 7, Subject of the amendment

Claims (1)

[Scope of Claims] (1) A circulating inventory containing a particulate cracking catalyst is circulated between a hydrocarbon cranking zone and a catalyst regeneration zone; palladium or a palladium compound in a fluid catalytic cracking process in which the sulfur content of the gas leaving the regeneration zone is controlled by the inclusion of a solid sorbent;
A sulfur dioxide oxidation promoter formed in close association with at least one other metal selected from the group consisting of platinum, osmium, iridium, rhenium and rhodium or a compound thereof, in association with an inorganic oxide support. An improved method characterized by making the reproduction band exist within the reproduction band. (2) Claim (1) in which the sulfur oxide sorbent comprises separate particles physically mixed with a cooking catalyst.
)the method of. (3) The method according to claim (1), wherein the sulfur dioxide oxidation promoter also acts as a carbon monoxide oxidation promoter. (4) Claims (1) in which the inorganic oxide support is a finely divided solid that is miscible with the circulating inventory and circulates it between the cracking zone and the regeneration zone.
)the method of. (5) The method according to claim (1), wherein the sulfur dioxide oxidation promoter is a combination of palladium or a palladium compound and one type of other metal or one type of compound of another metal. (6) The method of claim (5), wherein the other metal is platinum. (7) Claims in which the other metal is iridium (
Method 5). (8) Claims in which the other metal is rhodium (5)
)the method of. (9) Claims containing metals in a mutual ratio within the range of about 10:1 to about 1:10 by weight (
6), (7) or (8) method. (10) The total metal content of the promoter is within the range of about 0.01 to about 2% by weight, and the total metal content of the cracking catalyst is about o,
oi to about 100 ppm by weight. (11) The method according to claim (4), wherein the support is a porous amorphous cracking catalyst having friction resistance. (12) (a) a particulate cracking catalyst for cracking hydrocarbons in the absence of hydrogen; (b) a sulfur sorbent capable of sorbing sulfur trioxide; are different first particulate solids, and (0) palladium or a palladium compound, and platinum,
A catalyst different from the particulate cracking catalyst, comprising an inorganic oxide support in association with a metal mixture containing at least one other metal selected from the group consisting of osmium, iridium, rhenium and rhodium, or a compound thereof. 1. A composition useful for clarifying sulfur-containing hydrocarbons in the absence of added hydrogen, the composition comprising particulate solids of 2. (13) The first fine particulate solid is about 0.1-・10 by weight
Claims containing 0% reactive aluminum (1
2) Composition, substance. (14) the second particulate solid comprises palladium or a palladium compound and one other metal or a compound of one other metal, and the total metal content of the second particulate solid is within the range of about 0.01 to about 2% by weight of the cracking catalyst, and about 0.1 to about 110011 of the cracking catalyst.
The composition of claim (12) occupying pp. (15) Claims in which the other metal is platinum (14)
) composition. (16) The composition of claim (14), wherein the other metal is iridium. <17) Claims in which the other metal is rhodium (
14) Composition. (1B) The composition of claim (15), (16) or (17), wherein the metals are contained in a mutual ratio within the range of about 10:1 to about 1:10. (19)(a) A particulate cracking catalyst consisting essentially of a silica-containing cracking catalyst impregnated with an aluminum compound capable of sorbing sulfur oxides;
and (b) palladium or a palladium compound and platinum,
A second particulate, different from the particulate cracking catalyst, comprising an inorganic oxide support associated with at least one other metal or compound thereof selected from the group consisting of osmium, iridium, rhenium and rhodium. 1. A composition useful for cracking sulfur-containing hydrocarbons in the absence of added hydrogen, the composition comprising a sulfur-containing solid.